Field of the Invention
The present disclosure relates to the field of display technologies, and particularly, to a thin film transistor (TFT) and a method of manufacturing the same, and an array substrate and a display device comprising the thin film transistor.
Description of the Related Art
An organic light-emitting diode (OLED) display may be made to be lighter and thinner, has a larger visual angle and no radiation, and significantly saves electric energy. Thus, the organic light-emitting diode display dominates the flat panel display device market, and is considered as the most likely next generation of new flat panel display. In an Active matrix OLED, a thin film transistor is provided as a switch to control each pixel, and the thin film transistor generally comprises a gate electrode, a source electrode, a drain electrode, a gate insulating layer and an active layer.
Both oxides, such as an indium gallium zinc oxide (IGZO), an indium tin zinc oxide (ITZO) and the like, and amorphous silicon, can be used as materials for manufacturing the active layer of the thin film transistor. Compared to the amorphous silicon thin film transistor, the oxide thin film transistor has a carrier concentration which is about ten times of that of the amorphous silicon thin film transistor, and a carrier mobility which is 20 to 30 times of that of the amorphous silicon thin film transistor. Thus, the oxide thin film transistor can greatly increase charging and discharging rates to a pixel electrode through the thin film transistor and thus a response speed of the pixel, thereby achieving a quicker refresh rate. The oxide thin film transistor is applicable in situations where a quick response and a larger current are required, such as a high frequency, high resolution and large-sized display, an organic light emitting display or the like. Therefore, the oxide thin film transistor becomes a semiconductor component of the new generation of LCD and OLED display devices.
FIG. 1A is a schematic structural diagram of an etching barrier type oxide thin film transistor in prior arts, and FIG. 1B is a sectional view of the oxide thin film transistor taken along a line A-A′ shown in FIG. 1A. As shown in FIG. 1B, 110 indicates a substrate, 120 indicates a gate electrode, 130 indicates a gate insulating layer, 140 indicates an active layer, 150 indicates an etching barrier layer, and 160 indicates source/drain electrodes. In the existing oxide thin film transistor, since an oxide semiconductor layer is often made of an amorphous silicon oxide, it is difficult to form an ohmic contact between the oxide semiconductor layer and a source/drain (SD) metal layer, thereby resulting in a bad stability of the thin film transistor. In addition, a channel length of the thin film transistor will have an effect on an on-state current of the thin film transistor, that is, the smaller the channel length is, the larger the on-state current of the thin film transistor is. In the existing etching barrier type oxide thin film transistor, however, the etching barrier layer is formed before the source and drain electrodes, so that the channel length D1 (FIG. 1B) of the oxide thin film transistor corresponding to the size of the etching barrier layer is large, and the on-state current is small, which greatly degrades performances of the thin film transistor and is unfavorable for development of high-performance display devices.